A ball is thrown vertically upward from ground level
PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A ball is thrown vertically upward from ground level. Choose the upward direction as positive.
(i) Just after being released, at its highest point, and just before returning to the point of projection, state the direction (upward/downward) and sign (positive/negative) of the ball’s linear momentum.
(ii) Comment on the correctness of the statement: “The momentum of the ball decreases continuously during its ascent and becomes zero at the top.” Give reasons for your answer without using numerical calculations.
(iii) If, instead, the downward direction were taken as positive, how would the signs of the three momenta mentioned in part (i) change? Would any physical prediction about the motion be altered? Explain briefly.